What is Mondrian?

I've read the table of contents of the book on Manning page. But I have no idea what is Mondrian really about. When talking about big data, I usually think of Hadoop, MapReduce etc. When talking about analytic, I usually think about the data mining models, cluster, Nerual Network and ALM etc. Could you explain what is Mondrian really about?

In a nutshell, Mondrian is an engine for doing multi-dimensional analysis. So if you want to look at sales data, for example, you can answer questions like: how many products of each type did I sell last quarter, or who are my most profitable customers. The key is that the questions aren't known in advance. Mondrian provides an infrastructure for users to be able to ask their own questions against the data without having to write code or SQL queries.

It differs from big data in that it is not a storage mechanism, but rather a way to access information about the data. It differs from machine learning in that it's a tool for analysts.